I have spent the past 5ish years attempting without success to grow aerial roots on my ficus retusa bonsai. I have tried everything from wrapping in sphagnum moss, humidifiers, spray bottles, etc.

Over the past winter it grew several long, spindly branches which I intend to cut and scrape the tips, add rooting hormone, and bury under the soil in an attempt the grow roots. My hope is that in time these will root and become thicker.

i am attempting that right now... about 6 months ago i wired 2 branchlettes down and into the soil of a small tiger bark ficus (retusa)...

i simply stripped all the foliage, hit the tips with rooting hormone, wired them and buried them...

at this point they are still alive as they are creating new foliage which i continue to pinch off, because what we are trying to do is reverse the flow of energy and our mad horticulturist, leo s., thinks it is possible in theory to tell that branch that it is now feeding the branch to which it is attached rather than taking up nutrients from the original root system...

as of this writing, i am unsure yet what is happening underground, but i plan on repotting early summer and at that point i will see if it is working, after which i will do the same on a much larger tiger bark (as an aside, to be convincing, the branchlettes need to come straight down into the soil, with no visible curved bend such as mine)

so, while i can't say yet if it is successful, i can say to go for it... it can't hurt none...

I'm not at all sure you will get your tree's circulatory system to reverse course. After all it is done in different parts of the plant.

_________________Jim Lewis - lewisjk@windstream.net - Western NC - People, when Columbus discovered this country, it was plumb full of nuts and berries. And I'm right here to tell you the berries are just about all gone. Uncle Dave Macon, old-time country musician

my thoughts on reversing the system stem from colin lewis' analogy about the difference in circulatory systems between conifers and broadleaf trees...

conifers are like a train on a train track, being a simple two-way system with the train being very limited in where it can go... meaning one root feeds one branch... remove that root and you kill that branch... and visa versa

while broadleafs are more like cars on a freeway, with many routes available to get on & off the main system, detour around construction, etc... meaning if you cut a root another root can take over the feeding duties and visa versa...

i hope i got that right (maybe it was just junipers, rather than conifers in general)... but for a clearer explanation of that, along with a TON of other good info, i would recommend colins on-line course... best 25 bucks i spent on anything bonsai related, mainly because after viewing it, you can revisit it as often as you want, which i should now do (and no, i do not get kick backs for endorsements )

As to what Van is asking about ficus, I don't know that particular species but have read that consistently high humidity is a key for aerials, as in 70's% all year round, and protection from the sun drying them out. Maybe others can confirm or dispute that.

As to what Van is asking about ficus, I don't know that particular species but have read that consistently high humidity is a key for aerials, as in 70's% all year round, and protection from the sun drying them out. Maybe others can confirm or dispute that.

Depending on the size of the tree you can create a cheap greenhouse by using an inverted clear plastic storage tub. This creates the humid environment and has produced aerial roots on my ficus in the past. I typically have used this method in the winter to maintain humidity around my trees but if used outdoors in the summer I think you'd get many aerial roots. Watch for pests though.

Don't let the zone envy get out of hand. A branch will always be a branch. I doubt if you can change the circulation. If you can get a root to sprout during the winter, try training it through a straw.You can use a transparent container under lights in the winter. If you put a tree in it in the sun, it will burn to death.The species you are discussing, Chinese banyan (including tiger bark), is Ficus microcarpa. There is only one Ficus retusa in captivity, in Indonesia. It is not in the trade at all. They are all F. microcarpa.Iris